The present invention relates to electric plugs, and relates more particularly to such an electric plug which has a switch controlled to close/open the circuit.
A regular electric plug is generally comprised of a housing, a base mounted in the housing, two metal contact plates mounted inside the base and respectively connected to the two conductors of an electric wire, and two metal plates respectively connected to the metal contact plates and extending out of the base and the housing for connection to an electric power outlet. This structure of electric plug is not safe in use because it can not protect against an overload. In order to protect against an overload, fuse means may be installed. There is also known an electric plug having two plug holes at the rear end for the connection of an external electric plug. However, because the plug holes at the rear end of the electric plug are exposed to the outside, a child may insert a metal object into the plug holes to close the circuit, causing an electric shock.
According to one aspect of the present invention, the safety plug comprises a first metal contact plate and a second metal contact plate respectively connected to the two conductors of an electric wire, a first metal blade and a second metal blade for connection to an electric power outlet, a cartridge fuse connected between the second metal contact plate and the second metal blade, a switch controlled to force the first metal contact plate into contact with the first metal blade to close the circuit, and a base mounted within a housing to hold the aforesaid members on the inside. According to another aspect of the present invention, the base has a rear panel, and two plug holes on the rear panel for the insertion of an external electric plug to connect the first metal blade and the second metal blade. According to still another aspect of the present invention, a slide is mounted in the housing and moved to close/open the plug holes of the rear panel of the base.